A. Field of the Invention
The present invention relates to a solid type fabric-cleaning product, whose utility is as a pre-applied spotting agent for use prior to laundering or dry cleaning to facilitate the removal of stains and soil from selected pre-treated areas of the fabric. More particularly, the invention is directed to a solid laundry pre-spotter composition that includes sodium stearate, propylene glycol, a polyethylene glycol, an alkyl aromatic acid, a strong base, non-ionic surfactants, sodium bicarbonate-both in its free form and in an encapsulated form, an enzyme and water.
B. Description of the Prior Art
Compositions have long been used as pre-spotting preparations in the laundering and cleaning field. Such preparations have been applied to particular, selected stained or excessively soiled portions of clothing and other fabrics prior to laundering. Effective pre-treatment of this type increases the likelihood of removing the soils and stains from the fabric during the cleaning process.
Some of the pre-spotting compositions have included laundry enzymes of the type that have been shown to enhance the removal of foreign material, such as oil stains, other stains, and soil from fabrics. When enzyme systems are used, they are critically sensitive to the pH of the composition into which they are introduced.
Prior art "stain sticks" or pre-spotting compositions have included those having a sodium stearate matrix. However, those skilled in the art have long tried, and yet failed, to formulate a product which is a firm solid having an acceptable drop point and also has a pH below about 9.8, yet yielding when manual pressure is applied, a value reasonably expected to be compatible with enzyme activity. As discussed extensively in Sabol et al., U.S. Pat. No. 4,842,762 issued Jun. 27, 1989, many of the stick-type products based on sodium stearate have failed to achieve a good working balance of physical properties, such as hardness and drop point, with desirable chemical properties, such as a pH that falls within a range that is acceptable for enzyme activity.
Sabol et al. recommends the formation of sodium stearate in situ and the addition of various salts to selectively modify particular physical and chemical parameters of the composition, including texture, consistency, hardness, melting point and pH, to optimize the rheology and the softening range of the product. In particular, Sabol et al. teaches that the addition of a certain class of salts within a critical concentration range of from 1 to 4% by weight is necessary to achieve good physical and chemical properties for this type of product.
In co-pending U.S. patent application Ser. No. 07/901,785 filed on Jun. 22, 1992 by Mandy, entitled SOLID LAUNDRY PRE-SPOTTER COMPOSITION AND METHOD OF USE, now U.S. Pat. No. 5,288,420, issued Feb. 22, 1994 a solid laundry pre-spotter with optimum physical parameters was achieved, but without the necessity of adding a critical concentration of salt to a sodium stearate matrix composition. Simultaneously, the pH level was decreased to as low as 9.0, thereby enhancing enzyme activity while maintaining acceptable physical properties, such as hardness and drop point.
And in co-pending U.S. patent application Ser. No. 07/912,191 filed on Jul. 13, 1992 by Mandy, SOLID LAUNDRY PRE-SPOTTER COMPOSITION CONTAINING SODIUM BICARBONATE AND METHOD OF USE, now U.S. Pat. No. 5,288,421, issued Feb. 22, 1994 from which the present application claims the benefit of an earlier filing date, solid laundry pre-spotter compositions are taught that use sodium bicarbonate to decrease the pH level to below 9.0, and as low as 8.2, thereby enhancing enzyme activity while maintaining acceptable physical properties, such as hardness and drop point.
With the advent of encapsulation technology, new packaging techniques and other considerations have surfaced when formulating compositions for solid consumer products. Heretofore, however, such technology has not been used in connection with solid laundry pre-spotter stick compositions, especially in terms of encapsulating a sodium bicarbonate ingredient.